[all-commits] [llvm/llvm-project] d7a981: [AArch64] Fix variadic tail-calls on ARM64EC (#79774)

[Billy Laws via All-commits]

  Branch: refs/heads/release/18.x
  Home:   https://github.com/llvm/llvm-project
  Commit: d7a9810f9c14e6598265ab41519be9b861228450
      https://github.com/llvm/llvm-project/commit/d7a9810f9c14e6598265ab41519be9b861228450
  Author: Billy Laws <blaws05 at gmail.com>
  Date:   2024-03-11 (Mon, 11 Mar 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
    M llvm/test/CodeGen/AArch64/arm64ec-varargs.ll
    M llvm/test/CodeGen/AArch64/vararg-tallcall.ll

  Log Message:
  -----------
  [AArch64] Fix variadic tail-calls on ARM64EC (#79774)

ARM64EC varargs calls expect that x4 = sp at entry, special handling is
needed to ensure this with tail calls since they occur after the
epilogue and the x4 write happens before.

I tried going through AArch64MachineFrameLowering for this, hoping to
avoid creating the dummy object but this was the best I could do since
the stack info that uses isn't populated at this stage,
CreateFixedObject also explicitly forbids 0 sized objects.


  Commit: 42c599ab365b6d413d7e35a40f6e4ab98f523b67
      https://github.com/llvm/llvm-project/commit/42c599ab365b6d413d7e35a40f6e4ab98f523b67
  Author: Billy Laws <blaws05 at gmail.com>
  Date:   2024-03-11 (Mon, 11 Mar 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
    M llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll

  Log Message:
  -----------
  [AArch64] Fix generated types for ARM64EC variadic entry thunk targets (#80595)

ISel handles filling in x4/x5 when calling variadic functions as they
don't correspond to the 5th/6th X64 arguments but rather to the end of
the shadow space on the stack and the size in bytes of all stack
parameters (ignored and written as 0 for calls from entry thunks).

Will PR a follow up with ISel handling after this is merged.


  Commit: 89d543227a324d9925c68caf5d75c8c1e46c02a4
      https://github.com/llvm/llvm-project/commit/89d543227a324d9925c68caf5d75c8c1e46c02a4
  Author: Billy Laws <blaws05 at gmail.com>
  Date:   2024-03-11 (Mon, 11 Mar 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64Arm64ECCallLowering.cpp
    M llvm/lib/Target/AArch64/AArch64CallingConvention.td
    M llvm/test/CodeGen/AArch64/arm64ec-entry-thunks.ll

  Log Message:
  -----------
  [AArch64] Skip over shadow space for ARM64EC entry thunk variadic calls (#80994)

When in an entry thunk the x64 SP is passed in x4 but this cannot be
directly passed through since x64 varargs calls have a 32 byte shadow
store at SP followed by the in-stack parameters. ARM64EC varargs calls
on the other hand expect x4 to point to the first in-stack parameter.


Compare: https://github.com/llvm/llvm-project/compare/ea6c457b8dd2...89d543227a32

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